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Lecture 6

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Biological Sciences
Connie Potroff

1 Lecture 6 The Muscular System Axial & Appendicular Musculature **Assigned readings p.215-218 (articular form and function)? The Skeletal System: Articulations The body cannot move without joints Movements are linked to the range of joint action Joints (arthroses) are connections between bones that may or may not permit movement Two bones may be in direct contact with each other or separated by: Cartilage Fluid Fibrous tissue Joints are classified based on: Function Range of motion Structure Makeup of the joint Classification of Joints Joints can be classified based on their range of motion (function) Synarthrosis (immovable joint) Sutures (joints found only in the skull) Bones are interlocked together – sutural ligament, type of unossified connective tissue Gomphosis (joint between teeth and jaw bones) Periodontal ligaments of the teeth - fibrous *Synchondrosis (joint within epiphysis of bone) Binds the diaphysis to the epiphysis (syn – together, chondro – cartilage) *Synostosis (joint between two fused bones) Fusion of the three coxal bones – no boundary between fusion, totally rigid Amphiarthroses (slightly movable joints) *Syndesmosis (ligaments that connect two bones but limit their motion) Between the radius and ulna, between the tibia and fibula (desmos – band, ie. band of ligament) Symphysis (bones are separated by a wedge or pad of cartilage) Between the pubic bones of the two coxal bones and intervertebral discs – fibrous Diarthroses (freely movable joints) Also called synovial joints Typically found at the ends of long bones Examples of diarthroses joints: shoulder joint, elbow joint, hip joint, knee joint Synovial joints : Three main functions: 1. provide lubrication 2. nourish the chondrocytes ** 3. shock absorption All synovial joints have six basic characteristics: A joint capsule The presence of articular cartilages A joint cavity with synovial fluid – lubricates the surfaces of the articular cartilages and reduces friction, nourishes the chondrocytes by entering and exiting the © 2012 Pearson Education, Inc. 2 articular cartilage due to forces acting on the joint and acts as a shock absorber A synovial membrane Accessory structures (cartilage, ligaments, tendons, bursae sacs – small fluid filled pockets found where ligaments and tendons rub against other tissues to reduce friction) Sensory nerves and blood vessels Structural Classification of Synovial Joints Plane joints (gliding joints) monaxial – movement in only one plane Eg. Carpal/carpal – Tarsal/tarsal – Vertebrae/vertebrae – Clavicle/sternum Hinge joints Flexion and extension - monaxial o Eg. Elbow and knee Pivot joints Rotational movements including supination and pronation - monaxial Eg. Atlas/axis Condylar joints (ellipsoidal joints) Oval articular surface on one bone articulates with a depression on another bone, biaxial joint, movement in two planes *Eg. Radius/capitulum – Radius/carpals – Phalanges/metacarpals – Phalanges/metatarsals Saddle joints Biaxial joints that allow some circumduction, angular movement without rotation** Eg. Pollex/metacarpal Ball and socket joints Triaxial joints, angular movement and rotation Eg. Shoulder joint – Hip joint Introduction The skeletal muscle of the body can be subdivided into: Axial musculature Muscles that position the head and vertebral column Muscles that move the rib cage Appendicular musculature Muscles that stabilize or move the appendicular skeleton The Axial Musculature The axial muscles can be placed into four groups based on location or function Muscles of the head and neck Muscles of the vertebral column Oblique and rectus muscles Muscles of the pelvic floor Muscles of the Head and Neck Can be subdivided into several different groups Muscles of facial expression (mouth, eye, nose, scalp, neck) Extraocular muscles (muscles that control eye movement) Muscles of mastication (chewing) p.274 tb Masseter – elevates mandible and closes jaw, assists in protracting and retracting mandible and moving mandible from side to side (origin – zygomatic arch of zygomatic bone; insertion – mandible) Temporalis – elevates mandible and closes jaw, assists in retracting and moving mandible from side to side (origin – along temporal ljnes of skull; insertion – mandible) © 2012 Pearson Education, Inc. 3 Medial Pterygoid – elevates the mandible and closes the jaw, or moves the mandible side to side (origin – palatine bone/maxilla; insertion – mandible) *Lateral Pterygoid – opens jaw, protrudes mandible, or moves mandible side to side (origin – palatine bone/maxilla; insertion – mandible) Muscles of the tongue Muscles of the pharynx (pharyngeal constrictors, laryngeal elevators, palatal muscles) Muscles of the anterior neck p.277 tb Digastric – depresses mandible, opening mouth, and/or elevates larynx (*origin – mandible and temporal bone; insertion – hyoid bone) Sternocleidomastoid –together they flex the neck, alone one side bends neck toward shoulder and turns face to the opposite side, sterno = sternum, cleido = clavical, mastoid = mastoid process of temporal bone (origin – sternum and clavical; insertion – mastoid process of temporal bone) Sternohyoid – depresses hyoid bone and larynx (origin – sternum; insertion – hyoid bone) Sternothyroid – depresses hyoid bone and larynx (origin – sternum; insertion – thyroid cartilage of larynx) *Thyrohyoid – elevates larynx depresses hyoid bone (origin – thyroid cartilage; insertion – hyoid bone) *Stylohyoid – elevates larynx stylos = pillar or any slender pointed process also found on radius and ulna (origin – styloid process of temporal bone; insertion – hyoid bone) **Muscles of the Vertebral Column Back muscles form three distinct layers p.292-293 tb Superficial layer (extrinsic back muscles): move the neck Trapezius – extends neck (will come back to more actions for this muscle)(origin – occipital bone and spinous processes of thoracic vertebrae; insertion – clavicle and scapula) Latissimus dorsi – extension, adduction and medial (or internal) rotation at shoulder, “swimmer’s muscle” (origin: vertebrae; insertion: humerus) Levator scapulae – elev
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